Various arrangements are known in the art for securing the inner ring of a bearing assembly onto a shaft. Such arrangements have included shaft engaging set screws and shaft-surrounding locking collars. Such locking collars may include locking or tightening means, generally in the form of one or more locking screws. In the so-called SKWEZLOC® arrangement disclosed in U.S. Pat. Nos. 4,537,519 and 4,728,203, the inner ring has finger extensions which, when compressed with a screw operated locking collar, tightly grip and hold the shaft. This finger extension/locking collar combination enhances the concentricity of the inner ring with the shaft and facilitates rotation of the shaft at higher speeds.
An improved bearing locking collar is disclosed in U.S. Pat. No. 6,200,039 incorporated herein by reference, where a bearing assembly is provided wherein the locking collar is pre-assembled on the inner bearing ring at the factory and may remain properly positioned on the inner bearing ring during installation onto a shaft. In one aspect, the inner diameter of the annular locking collar is provided with a protrusion which extends radially inwardly. When the locking collar is disposed about the finger extensions of the inner ring, the protrusion is disposed within a recessed groove which extends at least partially along the collective outer annular surface defined by the finger extensions for precisely locating and orienting the collar. A locking screw is tightened to deform the finger extensions into secure engagement with the shaft. Typically, the locking collars are manufactured from straight bar stock having a generally square cross-section. The bar stock is typically bent nearly 360 degrees such that the ends of the bar nearly meet. When the bar stock is bent, stresses are introduced into the locking collar, particularly at the portion of the locking collar located opposite from the locking screw. When the locking screw is tightened to secure the locking collar, the ends of the bar stock are drawn together. This results in the introduction of even further stresses in the locking collar. As a result, the bar stock must have a sufficiently large cross-sectional area to handle the stresses that are introduced during the manufacture of the locking collar as well as during the tightening of the locking screw. Alternatively, a solid cylindrical bar or thick-walled tube can be cut to the width of the locking collar, and the center machined away to create the annular locking collar. Using this method wastes a significant amount of material, is time-consuming, and very costly, but does eliminate the stresses introduced from bending. Moreover, it is only practical to provide a locking collar with circular inner and outer surfaces.
In addition, as disclosed in U.S. Pat. No. 6,200,039, the recesses or protrusions provided in the locking collar to mate with the finger extensions of the inner bearing ring must be machined into the locking collar. If the recesses or protrusions are machined into the bar stock while it is still straight and prior to bending, then the protrusions or recessions may become deformed or non-uniform during the bending process. However, it is more difficult and more costly to machine the recesses or grooves after the bar stock has been bent, or during the machining of a cylindrical bar or thick walled tube.
Accordingly, it is desirable to provide a bearing locking collar where the stresses are reduced or eliminated during the process of manufacture. It is also desirable to provide an easier or less costly method of manufacture. It is also desirable to provide a locking collar having a reduced cross-sectional area to reduce material costs. It is further desirable to provide a locking collar where recesses or grooves may be more easily provided on the inner surface of the locking collar. Finally, it is desirable to provide a locking collar having performance enhancing geometries, and a cost-effective method of making locking collars having such geometries.